Conservation of Endemic Bartram's Bass: Nesting Microhabitat Use and Spatial Distribution with Congeners in the Savannah River Basin

Clemson University TigerPrints

All Theses Theses

12-2018

Emily Elizabeth Judson Clemson University, [email protected]

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Recommended Citation Judson, Emily Elizabeth, "Conservation of Endemic Bartram's Bass: Nesting Microhabitat Use and Spatial Distribution with Congeners in the Savannah River Basin" (2018). All Theses. 3255. https://tigerprints.clemson.edu/all_theses/3255

This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. CONSERVATION OF ENDEMIC BARTRAM'S BASS: NESTING MICROHABITAT USE AND SPATIAL DISTRIBUTION WITH CONGENERS IN THE SAVANNAH RIVER BASIN

A Thesis Presented to the Graduate School of Clemson University

In Partial Fulfillment of the Requirements for the Degree Master of Science Wildlife and Fisheries Biology

by Emily Elizabeth Judson December 2018

Accepted by: Dr. Brandon Peoples, Committee Chair Dr. Troy Farmer Mrs. Jean Leitner ABSTRACT

Bartram’s Bass Micropterus sp. cf cataractae is endemic to the Savannah River basin of South Carolina and Georgia. Bartram’s Bass is threatened by habitat alteration and hybridization with invasive Alabama bass (M. henshalli) and other non-native co- occurring congeners. This study aimed to identify reproductive habitat preference of this species, and factors contributing to its occurrence.

In Chapter 1 we identified Bartram’s Bass nesting preference throughout the upper portion of its native range. In spring/summer 2017 and 2018, snorkel surveys were performed in tributaries to quantify nesting microhabitat use of Bartram’s Bass. Zig-zag transects were used to locate nests and to quantify habitat availability. Nesting microhabitat parameters were recorded at each nest detected, and eggs were collected for genetic analysis. Average velocity at the 39 pure Bartram’s Bass nests observed was 0.09

± 0.02 m/s, SD, lower than average available velocity of 0.22 ± 0.01 m/s, SD (p=

0.0028). Average depth of nests was 0.70 ± 0.04 m, SD and was similar to those available 0.67 ± 0.02 m, SD (p= 0.6946). The substrates used in nests during both breeding years combined were primarily silt (36%), cobble (31%), and gravel (21%), whereas the most available substrates observed in transects were bedrock (23%) and cobble (23%) (P<0.0001). On average, nests were 1.84 ± 0.25 m from the nearest bank, and 4.67 ± 0.56 m from the nearest upstream flow influence. Differences between available and used habitat metrics indicate that velocity may be more important than depth or substrate when Bartram’s bass are selecting nest sites. While there is a relationship between substrate use and availability, we believe the main factor driving

ii substrate use is velocity and that certain substrate types are likely a byproduct of selection for velocity.

In Chapter 2 we determined the relative importance of abiotic factors and distance from reservoirs for predicting occurrence of Bartram’s Bass. From March to November of 2017 and 2018, individuals were collected from 160 sites across the upper Savannah

River basin. Sites represented a gradient of key abiotic variables—watershed- and riparian-scale land use types, ecoregions, stream gradient, and elevation. Genetic analysis of 241 individuals from 50 sites revealed Bartram’s Bass were present at 33 sites, and hybrids were present at 21 sites. Conditional inference trees were used to predict the variables that drive Bartram’s Bass distribution. Forested land cover at the watershed scale was the most significant predictor of Bartram’s Bass presence (p=0.0236). Pure individuals preferred sites of greater than 75% forested cover (p<0.001). In less forested watersheds, there was higher probability of finding pure Bartram’s Bass at sites with greater watershed areas (p<0.001), and increased distance from reservoirs (p<0.001).

Even when forested land cover was greater than 75% and stream gradients were low, sites closer to reservoirs were less likely to harbor pure fish (p<0.001). These results reflect the tradeoff between land cover and distribution for facilitating spread and hybridization of invasive fishes.

iii DEDICATION

I dedicate this thesis to the memory of my grandfather, Thomas Edward Judson, who passed away while I was completing this degree (3/19/1924- 2/11/2017). A farmer, hunter, angler, trapper, and lover of all things outdoors- I can only hope to live a life as full as his. I know this work would have made him proud.

I also dedicate this to my mother and father, Karen Hansen and Doug Judson, for instilling in me a passion for hard work, and for the outdoors; I would not be where I am today had it not been for your love and constant encouragement over the years.

iv ACKNOWLEDGMENTS

Thank you foremost to my advisor Dr. Brandon Peoples for accepting me as one of your first Master’s students, and for providing me the opportunity to study an amazing species.

This research has challenged me in ways I never thought possible, and allowed me to learn and grow in ways I didn’t know I needed to. I appreciate your patience and tactful support throughout the research and writing process. Thanks to my committee for their support and guidance, Dr. Troy Farmer and Mrs. Jean Leitner. Thank you to all who made this research possible, especially those who provided funding. I am forever grateful for the assistance of my field technicians: Jon Blalock, Alex Michaeli, Wesley Moore, and Luke Bell, as well as the many undergraduates who helped with lab work through

Creative Inquiry courses. Thank you to my fellow graduate students, Sam Silknetter, Josh

Vine, and Lauren Stoczynski for providing support and laughs through what might have otherwise been stressful times. Immense thanks also to Matt Walker, Tanya Darden, and

Kimberly Kanapeckas from the South Carolina Department of Natural Resources

(SCDNR) Hollings Marine Lab in Charleston, SC for processing all of my samples. The

Clemson office of SCDNR also provided enormous field assistance which I am grateful for, and I would especially like to thank Mark Scott, Kevin Kubach, Drew Gelder, and

Kenson Kanczuzewski for all the time and effort you put into my research.

Finally, thank you to my siblings, parents, and grandparents- for shaping me into who I am, loving and supporting me, and inspiring me to pursue my passions relentlessly.

v TABLE OF CONTENTS

Page

TITLE PAGE ...... i

ABSTRACT ...... ii

DEDICATION ...... iv

ACKNOWLEDGMENTS ...... v

LIST OF TABLES ...... vii

LIST OF FIGURES ...... viii

GENERAL INTRODUCTION ...... 1

CHAPTERS

I. NESTING MICROHABITAT CHARACTERISTICS OF BARTRAM’S BASS...... 6

Introduction ...... 6 Methods...... 10 Results ...... 13 Discussion ...... 20

II. SPATIAL DISTRIBUTION OF BARTRAM’S BASS AND CONGENERS IN THE SAVANNAH RIVER BASIN ...... 25

Introduction ...... 25 Methods...... 29 Results ...... 34 Discussion ...... 39

GENERAL CONCLUSION ...... 47

APPENDICES ...... 51

Appendix A: Supplemental Tables ...... 51

REFERENCES ...... 55

vi LIST OF TABLES Table Page

1.1 Table 1. Substrate categories and size ranges (mm) as derived from the Wentworth Scale (Wentworth 1922)...... 12

1.2 Table 2. Linear regression model results for water velocity used at Bartram’s Bass nests and available in transects in the upper Savannah River in 2017 and 2018...... 15

1.3 Table 3. Post hoc Tukey’s test on water velocity of nest use and habitat availability in the upper Savannah River in 2017 and 2018...... 16

1.4 Table 4. Linear regression model results for water depth used at Bartram’s Bass nests and available in transects in the upper Savannah River in 2017 and 2018 ...... 17

2.1 Table 1. List of watershed-scale predictor variables local-scale response variables used in the species distribution mode ...... 33

2.2 Table 2. Generalized linear mixed effects model results for Bartram’s Bass occurrence in the upper Savannah River ...... 37

vii LIST OF FIGURES Figure Page

1.1 Figure 1. Map of study area (top) and snorkel sites (bottom). Shaded areas of the map on the top left represent different states: North Carolina (dark gray), South Carolina (medium gray, and Georgia (light gray). Reservoirs of the upper Savannah River basin are labeled as letters: Jocassee (A), Keowee (B), Hartwell (C), and Russell (D)...... 9

1.2 Figure 2. Interaction of used and available velocities among two sampling years (2017 & 2018). Plotted values are least square means (±1 SE) from ANOVA model...... 15

1.3 Figure 3. Interaction of used and available depths among two sampling years (2017 & 2018). Plotted values are least square means (±1 SE) from ANOVA model ...... 17

1.4 Figure 4. Velocities and depths used at nests compared to those available based on habitat transect data for 2017 and 2018 nesting seasons combined. Bartram’s Bass were observed using water depths less than 1.5 m and water velocities less than 0.54 m/s. 33 of the 39 (85%) Bartram’s Bass nests were found in areas of less than 0.1 m/s velocity ...... 19

1.5 Figure 5. Substrates used at nests compared to those available based on habitat transect data for 2017 and 2018 nesting seasons combined. Though available substrate was dominated by bedrock and cobble, bass selected silt, cobble, and gravel more than they were available. Each category (“Available” versus “Used Among Nests”) represents a proportion of substrate availability, and when summed equals 1.0...... 20

2.1 Figure 1. Map of the upper Savannah River and fish collection sites. Land use is categorized in five categories: water, urban, forested, agriculture, and shrub/barren ...... 31

2.2 Figure 2. Map of sites in the upper Savannah River basin that are included in the analyses. Sites are color- coded with species present at each site; blue shades represent sites with Bartram’s Bass...... 36

2.3 Figure 3. Conditional inference tree classifying predictors of Bartram's Bass occurrence. Splits are based on variable-wise univariate significance tests at (alpha)= 0.05. Colors represent Bartram's Bass probability of occurrence (present is dark, absent is light). Numbers on the right of histograms represent predicted probability of Bartram’s Bass occurrence ...... 39

viii GENERAL INTRODUCTION

Species can be transported outside their native ranges by deliberate and unintentional introduction (Pyšek and Richardson 2010), natural introduction, or may become invasive within their native ranges (Scott and Helfman 2001). Species transported outside their native range carry several associated risks, and can present difficult management implications in recipient systems (Ricciardi et al. 2013). Nonnative species introductions can have detrimental impacts on native organisms, especially if they become invasive. However, only a fraction of introduced species successfully establish to invade a new system (Williamson and Fitter 1996; Allendorf and Lundquist 2003; Pyšek and Richardson 2010). The success of an invasive species relies on multiple factors, including the habitat and climate of the invaded system (Blackburn et al. 2011), traits of the invasive species (Huxel 1999; Blackburn et al. 2011), and propagule pressure

(Catford et al. 2009; Blackburn et al. 2011). When a species is identified as invasive, it has already established a self-sustaining population, and may have already caused damaging impacts on the native ecosystem (Ricciardi et al. 2013). Invasive species pose major threats to biodiversity, ecosystem stability, agriculture, fisheries and public health

(Lee 2002). Invasions cause communities to form which were originally absent in the ecosystem, resulting in novel interactions between species that would not have existed otherwise, such as competition between the nonnative and native species and hybridization, which may result in declines in native populations (Huxell 1999).

Hybridization is a major mechanism by which invasive species impact native species (Huxel 1999). Hybridization can occur in any system containing distinct species

1 capable of reproducing (Rhymer and Simberloff 1996; Huxel 1999), and is common across taxa (Simberloff 1996; Schwartz et al. 2004; Latch et al. 2006). It can occur at localized scales, or broadly over a species’ range. Hybridization can cause population decline, extinction, or loss of genetically distinct populations (Alvarez et al. 2015). The most common and detrimental effect of hybridization is the potential loss of the native genetic lineage (Hubbs 1955). Hybridization can cause ‘genetic swamping’ of native genomes through introgression, often resulting in ‘hybrid swarms’ in which fertile hybrids displace native parental populations (Anderson 1953). When gene pools intermix, genetic differentiation between parent species can be dissolved, and create higher inheritance of maladapted genes (Huxel 1999; Alvarez et al. 2015; Bolnick 2015).

Introgressive hybridization can result in extinction of native species, especially within endemic populations, and its most basic effects consist of erosion and degradation of native genotypes (Rhymer and Simberloff, 1996; Alvarez et al. 2015). Despite the dramatic effects hybridization can have on an ecosystem, the potential for and effects of interbreeding between nonnative and native individuals is an often overlooked impact of species invasions (Huxel 1999).

Ray-finned fishes (Actinopterygii) hybridize more frequently than other vertebrate classes, especially when co-occurring congeners use similar habitats for reproduction (Ryman and Utter 1986; Scribner et al. 2001). Hybridization is widespread among freshwater fishes, being common among many families including Esocidae,

Catostomidae, Leuciscidae, Centrarchidae, Salmonidae, and Percidae (Crossman and

Buss 1965; Greenfield et al. 1973; Keck and Near 2009; McKelvey et al. 2016).

2 Hybridization with invasive species poses a threat to many fish populations, especially those that are endemic and have relatively small ranges (Koppelman and Garrett 2002).

Although the processes and predictors of invasion have been widely studied in fishes

(Moyle and Light 1996; Moyle and Marchetti 2006; Rahel and Olden 2008), still little is known concerning how the mechanism of hybridization impacts the native fish assemblage after an invasion in a system (Avise et al. 1997; Barwick et al. 2006;

Pipas,and Bulow 2011; Peterson 2015).

The black basses (Centrarchidae: Micropterus) include some of the most popular sportfishes in the United States, and congruently the most widely introduced species

(Jackson 2002; Peoples and Midway 2018).There are currently nine recognized species of black bass in the southern US, including the widely sought after Alabama Bass (M. henshalli), Florida Bass (M. floridanus), Largemouth Bass (M. salmoides), Spotted Bass

(M. punctulatus), and Smallmouth Bass (M. dolomieu), and more narrowly distributed

Redeye Bass (M. coosae), Shoal Bass (M. cataractae), Guadalupe Bass (M. treculi), and

Suwannee Bass (M. notius) (Ramsey 1973; Koppelman and Garrett 2002). However, other taxa have been proposed as distinct species, including the Cahaba Bass (M. cahabae), Chattahoochee Bass (M. chattahoochae), Choctaw Bass (M. haiaka),

Tallapoosa Bass (M. tallapoosae), Warrior Bass (M. warriorensis), Altamaha Bass (M. sp. Cf M. coosae), Bartram’s Bass (M. sp. Cf M. cataractae), and Neosho Smallmouth

Bass (M. dolomieu velox). Numerous introductions of the more cosmopolitan black basses have led to widespread hybridization and introgression with the rarer black basses

(Avise et al. 1997; Koppelman and Garrett 2002; Barwick et al. 2006; Bangs et al. 2017).

3 For example, Guadalupe Bass, native to the Edward’s Plateau of Texas, has become extirpated in parts of its historical range due to introgression with the nonnative

Smallmouth Bass (Whitmore 1983; Littrell et. al. 2007), and Shoal Bass are threatened by hybridization with Spotted Bass (Avise et. al. 1997; Alvarez et. al. 2015).

A species of particular interest is Bartram’s Bass, an endemic to the Savannah

River basin of South Carolina and Georgia, USA. Individuals have been commonly referred to throughout its range as the Redeye Bass. However, Freeman et al. (2015) identified this species to be more closely related to Shoal Bass, and supported the elevation of Bartram’s Bass to species status. The range of Bartram’s Bass extends from below the fall line of the mainstem Savannah River to the cool, medium-to-high gradient stream segments typically found above the fall line (Leitner et al. 2015; Oswald et al.

2015). It has been introduced in the Saluda River of the Santee drainage (Bettinger 2015).

Bartram’s Bass face a multitude of threats including poor land-use practices, and hybridization with congeners, including the Smallmouth Bass and the Alabama Bass

(Oswald et al. 2015; Bangs et al. 2017).

Alabama Bass were introduced into the Savannah River basin in the 1980s by anglers to create a local reservoir sport fishery for the species (Oswald 2007). Alabama

Bass have since become widespread in the upper Savannah River reservoirs (Bangs et al.

2017), and are now colonizing the tributaries associated with those reservoirs (Leitner et al. 2015). Bartram’s Bass populations currently thrive in tributaries, and it is speculated that their populations have been restricted farther upstream since Alabama Bass have

4 invaded (Oswald et al. 2015). Bartram’s Bass and Alabama Bass hybrids have been found in the tributaries; however, it is unknown to what extent hybridization is occurring.

Understanding microhabitat preference is particularly important for native and nonnative congeners that hybridize (Todd and Rabeni 1989; Orth and Newcomb 2002;

Perkin et al. 2010). Microhabitat preference can help determine what is enabling two species to hybridize, and thus is an effective indicator of an isolating mechanism as different species occupying the same area may utilize similar water velocities, depths, and substrate (Perkin et al. 2010). Quantifying reproductive microhabitat requirements can serve as a first step toward identifying reproductive isolating mechanisms (Rosenfeld

2003). It will also be useful to identify how future land use changes might impact

Bartram’s Bass nesting habitat and contribute to further degradation. Although studies assessing other fluvial basses’ microhabitat use have been conducted (Saunders et al.

2002; Perkin et al. 2010; Bitz et al. 2015); there is currently no knowledge of Bartram’s

Bass reproductive preferences. Accordingly, the first objective of this study is to identify the nesting microhabitat selection of Bartram’s Bass.

In the case of hybridization with a nonnative species, it is imperative to identify areas for management that may favor the native species (Huxel 1999; Rosenfeld 2003;

Perkin et al. 2010). Determining the habitats and environmental factors that best predict

Bartram’s Bass presence will be vital in managing habitat for the Bartram’s Bass in the future. Accordingly, the second objective of this study is to assess the spatial patterns of hybridization between Bartram’s Bass and invasive Alabama Bass.

5 CHAPTER ONE

NESTING MICROHABITAT CHARACTERISTICS OF BARTRAM’S BASS

Introduction

Fishes require a variety of habitats to meet life history requirements over their lifespan; habitats for key activities such as feeding, spawning, and sheltering vary through space and time (Schlosser 1991; Fausch et al. 2002). Identifying reproductive microhabitat requirements is particularly important, as this activity sets the context for all other life stages (Balon 1975). Understanding spawning microhabitat preferences of fishes allows for prediction of population- (Winemiller 2005) and community-level

(Berkman and Rabeni 1987) responses to environmental change, and provides key insight into the conservation and management of imperiled fishes (Johnston 1999; Rosenfeld

2003). This is particularly true for imperiled fishes that are threatened by hybridization with nonnative congeners (Todd and Rabeni 1989; Orth and Newcomb 2002; Perkin et al.

2010). Understanding spawning microhabitat requirements can be the first step toward identifying potential disruption of genetically isolating barriers that facilitate hybridization.

The black basses (Centrarchidae: Micropterus) include some of the most popular sportfish species in the United States. Currently, there are nine recognized species of black bass in the southern US (Near et al. 2003, Baker et al. 2013; Tringali et al. 2015), but approximately twenty may actually exist (Tringali et al. 2015). A few species in this genus have large native range sizes, but several others are restricted to single or a few river basins in the southeastern US. Because of their popularity, the black basses are

6 among the most widely introduced freshwater fish species in the world (Jackson 2002;

Peoples and Midway 2018). Due to widespread introductions of some black bass species outside their native ranges, many of the endemic black basses in the southeastern US are threatened by hybridization with cosmopolitan species such as Spotted Sass M. punctulatus, Alabama Bass M. henshalli, Smallmouth Bass M. dolomieu, Florida Bass M. floridanus, and Largemouth Bass M. salmoides (Avise et al. 1997; Koppelman and

Garrett 2002; Barwick et al. 2006; Bangs et al. 2017). Although spawning microhabitats have been quantified for numerous species (Saunders et al. 2002; Dauwalter and Fisher

2007; Strong et al. 2010; Bitz et al. 2015), large gaps remain for many others.

One understudied southeastern species is Bartram’s Bass, an endemic of the

Savannah River basin of South Carolina and Georgia (Freeman et al. 2015; Leitner et al.

2015; Oswald et al. 2015). Bartram’s Bass is threatened by habitat alteration and hybridization with the nonnative congeners Alabama Bass and Smallmouth Bass

(Barwick et al. 2006; Oswald et al. 2015; Bangs et al. 2017). Alabama Bass were introduced into the Savannah River basin in the 1980s by anglers to create a local sport fishery for the species (Oswald 2007). Alabama Bass have since become widespread in the upper Savannah River basin, and are now colonizing the tributaries where Bartram’s

Bass occur (Leitner et al. 2015). Smallmouth Bass were introduced in mainstem of the middle Savannah River near Augusta, GA in the late 1990s, and have been annually stocked in Lake Jocassee by the South Carolina Department of Natural Resources (Bangs et al. 2017) (Figure 1). Identifying spawning microhabitat preference of Bartram’s Bass throughout its range will be a critical first step to understanding the mechanisms that

7 drive its imperilment through hybridization with nonnative congeners. Accordingly, the objective of this study was to quantify the spawning microhabitat preferences for key variables (namely depth, flow velocity, and substrate types) of Bartram’s Bass in the upper Savannah River.

8 Figure 1. Map of study area (top) and snorkel sites (bottom). Shaded areas of the map on the top left represent different states: North Carolina (dark gray), South Carolina (medium gray, and Georgia (light gray). Reservoirs of the upper Savannah River basin are labeled as letters: Jocassee (A), Keowee (B), Hartwell (C), and Russell (D).

9 Methods

Study Area

The Savannah River basin spans 27,394 km2, and forms the border between the

Georgia and South Carolina. It encompasses 15,076 km2 in eastern Georgia, 11,865 km2 in western South Carolina, and 453 km2 in southwestern North Carolina. There are four large impoundments in the upper Savannah River basin: lakes Jocassee, Keowee,

Hartwell, and Russell (Figure 1). Land use in the upper Savannah River basin consists of

55.3% forested land, 27.4% agricultural land, 9.3% urban land, 5.7% water cover, 1.7% forested wetland, and 0.6% barren land (DHEC 2017). The upper Savannah River is located in the Southern Blue Ridge Escarpment and upper southern Piedmont ecoregions

(Omernik 1987) above the fall line. The Piedmont is heavily impacted by development and urbanization, whereas the uplands of the Blue Ridge that make up the most northern reaches of the Savannah River basin are heavily forested and less impacted (SCDHEC

2017). The inner and outer Piedmont regions make up most of the upper Savannah River watershed (Omernik 1987). Below the fall line, the Savannah flows through the

Southeastern Plains and Southern Coastal Plain regions (Omernik 1987). This study included tributaries of the upper Savannah River basin of Georgia and South Carolina,

USA.

Field Methods

We surveyed 27 sites (300-m reaches) in upper Savannah River tributaries to quantify bass nesting microhabitat preference (Figure 1). Sites were selected for low turbidity to facilitate snorkeling, considering access constraints. We selected sites across

10 a gradient of stream size, land use, and distance from impoundments. HOBO temperature loggers were deployed at the downstream and upstream-most sites on each stream. Daily discharge for each stream was obtained from U.S. Geological Survey gauges. Water data was obtained from the USGS 02177000 Chattooga River flow gage near Clayton, GA which was used as a reference site for snorkeling conditions.

Three-person crews surveyed two-to-three sites each day via snorkeling from mid-April to mid-July of 2017 and 2018. Each site was visited at least three times throughout the duration of each season to ensure as many nests were detected as possible.

Each time a site was revisited, previous nests found at those sites were examined to ensure we did not sample the same nest twice. Crews worked upstream in a zig-zag pattern to locate nests (Thurow et al. 2013). A nest was evidenced by a guarding male

(Enriquez et al. 2016), or by the detection of eggs scattered on substrate with subsequent observation of a guarding bass. Once a nest was detected, it was marked and georeferenced. Photos and videos were taken to capture nesting activity and behavior of any tending adult males. Workers then returned to finish the transect, and revisited nests to collect eggs and habitat data upon completion of the survey.

Upon returning to a nest, we attempted to capture the guarding adult male off the nest using hook-and-line sampling (Lukas and Orth 1995). The nest was guarded by field crew members during the guarding males’ absence. We collected a pectoral fin clip of the parent for genetic analysis, and measured total length (mm) and weight (g) of each fish.

Depth (m), velocity (m/s), and ten substrate samples (mm) were then recorded at each nest (Dauwalter and Fisher 2007). We categorized substrate measurements based on a

11 modified Wentworth scale (Table 1). Nests with eggs broadcasted over detritus (dead organic material) and silt were categorized together in the silt category. Nest widths were measured on axes parallel and perpendicular to flow. We also measured distance (m) from nest location to the nearest upstream flow influence (i.e. boulder or large woody debris), and distance to the nearest bank (m) (Dauwalter and Fisher 2007). At least ten eggs were collected at each nest and preserved in 200-proof ethyl alcohol for genotyping.

We measured overall available habitat on transects at each nest location. Some transects applied to multiple nests, if those nests were within 10 m of one another. Depth (m), velocity (m/s), and substrate based on the same categorical scale as nests (Table 1), was measured at ten equidistant points along each transect.

Table 1. Substrate categories and size ranges (mm) as derived from the Wentworth Scale (Wentworth 1922).

Substrate Category Size of aggregate (mm) Bedrock Embedded rock Boulder > 256 Cobble 64 - 256 Gravel 2 - 64 Sand 0.06 - 2 Silt < 0.06

Analyses

Species identities had been developed using molecular tools described by Bangs et.al. (2017). Fin clips and egg samples from nests were processed at the Hollings Marine

Laboratory in Charleston, SC in the South Carolina Department of Natural Resources

Marine Resources Research Institute. Only nests identified as pure Bartram’s Bass were

12 included in the following analyses, this determination was based on all 10 analyzed eggs amplifying as pure.

We compared nesting microhabitat variables (depth, velocity, and substrate) to transect data to examine spawning microhabitat specificity, and to identify differences between available and used habitats. Depth and velocity variables were examined for normality, then log-transformed. We used the lmerTest package in R version 3.4.3 (R

Development Core Team, 2017), to fit linear mixed effects models to identify differences in measurement location (nest vs. transect), nesting season (2017 and 2018), and their interaction for depth and flow velocity, separately. These models contained a random intercept of nest identity to account for non-independence of measurements at nests and paired transects. We used the multcomp package to conduct post hoc means comparisons in a conservative Tukey’s test on velocity for models with significant interactive effects of sample location and spawning year. We used a chi-squared analysis to determine substrate use versus availability within individual breeding seasons and seasons combined.

Results

Nesting activity was observed from 16 May to 13 June in 2017, and from 5 May to 23 June in 2018 when water temperatures were around 20°C. We located 75 nests, 34 at 6 sites in 2017, and 41 nests at 11 sites in 2018. Nests were found within 7 tributaries.

Of those, 39 were identified as pure Bartram’s Bass; only these were included in analyses.

13 High water events that created dangerously high water levels and increased turbidity impacted our ability to survey during portions of both the 2017 and 2018 sampling seasons. Between 20 May and 30 May 2017, and 3 June and 10 June 2017, no surveys were conducted due to rain events. These 2017 rain events resulted in discharges greater than 800 cfs for eight consecutive days in May, as recorded at USGS 02177000

Chattooga River flow gage near Clayton, GA, which was used as a reference site for snorkeling conditions. Additionally, for 5 days in the beginning of June discharge was between 400 and 700 cfs. Just two nests were found (on 25 May 2018) between 14 May

2018 and 7 June 2018 due to similar rain events as those that occurred in 2017; 2018 rain events resulted in discharge greater than 1,000 cfs for 23 consecutive days (15 May to 6

June 2018).

We observed Bartram’s Bass spawning in pockets comprised of slow water and variable depths close to the banks. Some microhabitats were used for nesting in both

2017 and 2018. However, we cannot determine whether the same individuals were returning to the same area to spawn. Main effects of measurement location show that

Bartram’s Bass chose significantly lower water velocities for nesting across 2017 and

2018 (x̄ = 0.09 ± 0.02 m, SD) than those available (x̄ = 0.22 ± 0.01 m, SD) (p= 0.0028).

The interaction effect between measurement location and year was significant for velocity (F1, 368 = 4.21, p= 0.0408) (Table 2). A post hoc Tukey’s test on velocity revealed a significant difference between used and available velocities in 2018

(p<0.0001), and that Bartram’s Bass selected for significantly slower velocities for nesting in 2018 (x̄ = 0.01 ± 0.001 m/s, SD) than 2017 (x̄ = 0.12 ± 0.03 m/s, SD)

14 (p=0.0304) (Table 3). The range of available velocities was similar between years (Figure

2).

Figure 2. Interaction of used and available velocities among two sampling years (2017 & 2018). Plotted values are least square means (± standard error) from ANOVA model.

Table 2. Linear regression model results for water velocity used at Bartram’s Bass nests and available in transects in the upper Savannah River in 2017 and 2018.

Effect F1, 368 p Transect 23.0 <0.001 Year 6.9 0.0091 Transect: Year 4.2 0.0408

Table 3. Post hoc Tukey’s test on water velocity of nest use and habitat availability in the upper Savannah River in 2017 and 2018.

Effect Parameter estimate Std. Error Z1, 407 p 2018 Nest: 2017 Nest -0.15 0.06 -2.7 0.0304 2017 Transect: 2017 Nest 0.06 0.03 2.4 0.0596 2018 Transect: 2018 Nest 0.17 0.04 4.1 <0.001

Bartram’s Bass did not select for specific water depths for nesting (x̄ = 0.70 ± 0.04

m, SD) compared to those available (x̄ = 0.67 ± 0.02 m, SD) (p= 0.6946), although there

was a significant difference in available depth between years (F1, 370=11.53, p=0.0008)

(Table 4). No interaction was found between measurement location and year for depth

(F1, 370=0.19, p=0.6635). On average, Bartram’s Bass utilized shallower depths in 2018

(2017: x̄ = 0.76 0.04 m; 2018: x̄ = 0.54 ± 0.09 m), but available depths in 2018 (x̄ = 0.76 ±

16 0.03 m) were significantly shallower than those in 2017 (x̄ = 0.46 ± 0.03 m; p=0.0008)

(Figure 3).

Figure 3. Interaction of used and available depths among two sampling years (2017 & 2018). Plotted values are least square means (± standard error) from ANOVA model. Table 4. Linear regression model results for water depth used at Bartram’s Bass nests and available in transects in the upper Savannah River in 2017 and 2018.

Effect F1, 370 p Transect 1.9 0.1722 Year 11.5 0.0008 Transect: Year 0.19 0.6635

17 Bartram’s Bass used a variety of substrates for nesting, largely dependent upon those available in the slow velocity pockets they select for. The preferred substrate used in nests in both breeding years combined was primarily silt (36%), cobble (31%), and gravel (21%), whereas the most available substrate observed in transects was bedrock

(23%) and cobble (23%). Bedrock and cobble were the most available substrates in both

2017 (bedrock, 19%; cobble, 22%) and 2018 (bedrock, 34%; cobble, 26%). However, in

2017 bass used silt (41%) and cobble (41%) habitats more than they were available (silt,

9%; cobble, 22%) (p<0.0001), and in 2018 they used gravel (58%) and silt (25%) more than they were available (gravel, 8%; silt, 16%) (p<0.0001) (Figure 5). On average, nests were 1.84 ± 0.25 m from the nearest bank, and 4.67 ± 0.56 m from the nearest upstream flow influence.

Figure 4. Velocities and depths used at nests compared to those available based on habitat transect data for 2017 and 2018 nesting seasons combined. Bartram’s Bass were observed using water depths less than 1.5 m and water velocities less than 0.54 m/s. 33 of the 39 (85%) Bartram’s Bass nests were found in areas of less than 0.1 m/s velocity.

Figure 5. Substrates used at nests compared to those available based on habitat transect data for 2017 and 2018 nesting seasons combined. Though available substrate was dominated by bedrock and cobble, bass selected silt, cobble, and gravel more than they were available. Each category (“Available” versus “Used Among Nests”) represents a proportion of substrate availability, and when summed equals 1.0.

Discussion

Slow water velocities appeared to be the strongest microhabitat variable selected by nesting Bartram’s Bass in the upper Savannah River. Of the 39 pure nests found over both seasons, 33 (85%) occurred in velocities less than 0.10 m/s. Placement of nests also indicated that slow velocities may be a key requirement for nest sites. Individual nests were consistently located near the shore, and downstream of a major flow influence in pockets of slow water velocity which served as refugia from fluctuating water current.

Although a few nests were found in higher velocities (0.30-0.60 m/s), these were observed just after large rain events, suggesting that it is unlikely Bartram’s Bass would

20 select these higher velocities at baseflow conditions. The conclusion that lower velocities will be selected for when they are available was also supported by interannual difference in water velocities measured at nest sites. During the 2018 nesting season, when numerous rain events occurred, Bartram’s Bass always selected for areas of slower water velocities compared to 2017 which was a drier spring. Results of this study are similar to other studies that investigated nesting and seasonal use preferences of other other riverine black basses. Strong (2010) found that Suwannee Bass in Ichetucknee River, FL nest in similar water velocities (x̄ = 0.01 m/s). Smallmouth Bass in riverine environments have been observed nesting in high-flow refuge pockets of less than 0.03 m/s (Lukas and Orth

1995). Earley and Sammons (2015) observed Alabama Bass using slower water velocities associated with large woody debris (LWD) year round, although this study did not specifically address nesting preference. Largemouth Bass in lotic streams have been observed nesting in pools near the bank (Jenkins and Burkhead 1994). Given that

Bartram’s bass appears to select for low velocity habitats, it seems logical that high velcity discharge events may negatively affect recruitment if such events reduce nesting success. While this hypothesis was not investigated in the current study, some Shoal Bass and Smallmouth Bass populations have been negatively impacted by flashy hydrology due to impacted recruitment (Lukas and Orth 1995; Taylor et al. 2018).

Although results suggest Bartram’s Bass do not select for a narrow range of depth, 90% of nests were found in less than a meter of depth. Bartram’s Bass nested in a wide range of depths (0.27 m to 1.45 m) that were similar to overall availabile depths.

This is similar to the Suwannee Bass, which also nest in a wide range of depths (0.33 m

21 to 1.37 m) (Strong 2010). Smallmouth bass have, conversely, been observed nesting at depths higher than those observed in this study (x̄ = 1.09 ± 0.28 m) (Lukas and Orth

1995). Alabama Bass have been observed using depths greater than 1.09 m in spring and summer, which suggests they may use greater depths for nesting (Earley and Sammons

2015).

Bartram’s Bass selected for silt, gravel, and cobble in greater proportion than they were available during both nesting seasons. Bass used smaller substrates than in 2018, consistent with the slower microhabitats they selected overall. We observed bass nesting over all substrate categories, depositing eggs in both defined bowls or broadcasting them over bedrock and detritus. Thus, while the substrate selection results are statistically significant, they are not likely biologically significant. Bartram’s bass likely do not actively seek out particular substrates, but instead seem to select whatever substrate is available, given the optimal current velocity and distance from bank or shelter. Earley and Sammons (2015) obseerved Alabama Bass using a variety of substrates throughout nesting season, however they used bedrock more than anything else in spring and summer. Smallmouth Bass have been observed prefering rocky substrates in high current velocities (Rankin 1986; Todd and Rabeni 1989), and Spotted Bass prefer fine substrate and woody debris (Scott and Angermeier 1998).

The results of this study offer insight into the reproductive life history of

Bartram’s Bass and how important it is to study spawning activity throughout multiple nesting seasons. By observing a nesting season with increased rainfall in 2018, we were able to see that Bartram’s Bass responded by selecting pools of slower moving water in

22 every nesting attempt documented. Bartram’s Bass exhibited advantageous strategies to natural reproduction, evidenced by the numerous spawning events that coincided with flow fluctuations, and the selection of flow refuge areas in the year of higher flow.

Because annual stochastic events are typical throughout the Bartram’s Bass range in the

Savannah River, access to quality nesting areas is crucial to maintaining stable populations (Orth and Newcomb 2002). Due to the limited range of Bartram’s Bass and potential for future habitat degredation, managers should carefully consider protecting and restoring important nesting microhabitat for this species in the Savannah River.

Bartram’s Bass nest characteristics differed starkly from those observed in the

Shoal Bass, which share a most recent common ancestor (Freeman et al. 2015). Bartram’s

Bass nest bowls ranged from 10 cm to 95 cm in diameter, whereas Shoal Bass nests were typically contained within 30 cm diameter with no obvious concave profile (Bitz et al.

2015). Shoal Bass make long migrations to spawning shoals in the spring before nesting

(Sammons and Goclowski 2012; Goclowski et al. 2013). While movement of Bartram’s

Bass remains unstudied, most Bartram’s Bass nests did not use shoal structures, even when available. Shoal Bass also nest in areas directly behind flow influences or upstream of a riffle, typically closer to swifter water current, and select sand-gravel substrates (Bitz et al. 2015). Conversely, Bartram’s Bass nest closer to shore and prefer silt, cobble and gravel substrates. These results indicate that assuming ecologogical requirements from phylogenetic relationships may be problematic in this group of fishes. Understanding species-specific requirements for reproductive habitat use and other life history requirements will be critical for conserving endemic black basses.

23 The black bass clade is made up of both rare endemics and highly saught-after sport fish species, many of which co-occur and share similar habitats (Jackson 2002). In areas where nonnative congeners have been introduced, the use of similar habitats for reproduction poses a major potential risk of genetic introgression (Anderson 1953; Todd and Rabeni 1989; Perkin et al. 2010). Future work should identify nonnative black bass species nesting preferences in the upper Savannah River. This study can serve as a model for future research in areas where these populations persist in conjunction with nonnative species, further allowing us to assess how species’ microhabitat selection may drive hybridization.

24 CHAPTER TWO

SPATIAL DISTRIBUTION OF BARTRAM’S BASS AND CONGENERS IN THE

SAVANNAH RIVER BASIN

Introduction

Species can be transported outside their native ranges by deliberate and unintentional introduction (Pyšek and Richardson 2010), natural introduction, or may become invasive within their native ranges (Scott and Helfman 2001). Nonnative species introductions can have detrimental impacts on native organisms, although only a fraction successfully establish and become invasive (Williamson and Fitter 1996; Allendorf and

Lundquist 2003; Pyšek and Richardson 2010). Invasive species pose major threats to biodiversity, ecosystem stability, agriculture, fisheries and public health (Lee 2002).

Invasions cause communities to form which were originally absent in the ecosystem, resulting in novel interactions between species that would not have existed otherwise, such as competition between the nonnative and native species, declines in the native populations, and hybridization (Huxel 1999).

Hybridization is a major mechanism by which invasive species impact native species (Huxel 1999). Hybridization can occur in any system containing distinct species capable of reproducing (Rhymer and Simberloff 1996; Huxel 1999), and is common across taxa (Simberloff 1996; Schwartz et al. 2004; Latch et al. 2006). It can occur at localized scales, or broadly over a species’ range depending on abiotic context and dispersal ability. Dispersal ability of fish depends on access to upstream environments, often restricted by barriers (waterfalls, dams, etc.); these barriers can sometimes be a

25 beacon of hope in the case of hybridization, preventing a nonnative species from accessing possible refuge habitats where natives may hold out. Extensive hybridization and subsequent introgression can result in population decline, loss of genetically distinct populations, or extinction (Rhymer and Simberloff 1996; Alvarez et al. 2015).

Hybridization can cause ‘genetic swamping’ of native genomes through introgression, often resulting in ‘hybrid swarms’ in which fertile hybrids displace native parental populations (Anderson 1953). In cases of extensive introgression, genetic differentiation between parent species can be dissolved, creating higher inheritance of maladapted genes

(Huxel 1999; Alvarez et al. 2015; Bolnick 2015). Despite the dramatic effects hybridization can have on an ecosystem, the potential for and effects of interbreeding between nonnative and native individuals is an often overlooked impact produced by species invasions (Huxel 1999).

Catostomidae, Leuciscidae, Centrarchidae, Salmonidae, and Percidae (Crossman and

Buss 1965; Greenfield et al. 1973; Keck and Near 2009; McKelvey et al. 2016;

Eschenroeder et al. 2018). Scribner et al (2001) identified nearly 200 fish species that are threatened by hybridization. Hybridization with invasive species poses a threat to many fishes, especially those with relatively small ranges (Koppelman and Garrett 2002).

Although the processes and predictors of invasion have been widely studied in fishes

26 (Moyle and Light 1996; Moyle and Marchetti 2006; Rahel and Olden 2008), still little is known concerning how the mechanism of hybridization impacts the native fish assemblage after an invasion in a system (Avise et al. 1997; Barwick et al. 2006; Jelks et al. 2008; Pipas,and Bulow 2011; Peterson 2015).

Black basses (Micropterus spp.) are an ideal group for evaluating landscape-level drivers of hybridization as many species represent small endemic populations of limited distribution, while others are heavily introduced outside their native ranges (Jackson

2002; Oswald 2007; Diedericks et al. 2018). The black basses (Centrarchidae:

Micropterus) include some of the most widespread and popular sportfish species in the

United States, and congruently the most widely introduced species (Jackson 2002;

Peoples and Midway 2018). Currently, there are nine recognized species of black bass in the southern US (Near et al. 2003, Baker et al. 2013; Tringali et al. 2015), but approximately twenty may actually exist (Tringali et al. 2015). A few species in this genus have large native range sizes, but several others are restricted to single or a few river basins in the southeastern United States. Due to widespread introductions of some black bass species, many of the endemic black basses in the southeastern US are threatened by hybridization with cosmopolitan species such as Spotted Sass M. punctulatus, Alabama Bass M. henshalli, Smallmouth Bass M. dolomieu, and

Largemouth Bass M. salmoides (Avise et al. 1997; Koppelman and Garrett 2002;

Barwick et al. 2006; Bangs et al. 2017). For example, Guadalupe Bass, native to the

Edward’s Plateau of Texas, has become extirpated in parts of its historical range due to introgression with the nonnative Smallmouth Bass (Whitmore 1983; Littrell et. al. 2007),

27 and Shoal Bass are threatened by hybridization with Spotted Bass (Avise et. al. 1997;

Alvarez et. al. 2015). The transplant of some endemic species have also lead to introgression with more cosmopolitan native black bass (Pipas and Bulow 2011). Black basses are particularly prone to intrageneric hybridization due weak reproductive barriers that allow native and nonnative individuals to reproduce viable offspring (Littrell et al.

2007; Alvarez et al. 2015; Koppelman 2015; Bangs et al. 2017), and hybridization is frequently documented among this group of congeners (Whitmore 1983; Oswald et al.

2015; Dakin et al. 2015). Many studies have also investigated introgression and/or extinction by hybridization (Avise et al 1997; Barwick et al. 2006; Littrell et al. 2007), but studies regarding the landscape-level factors that drive hybridization in fishes have largely been limited to evaluation of impacts on trout populations (Hitt et al. 2003; Boyer et al. 2008; Muhlfeld et al. 2009; Marie et al. 2012; Muhlfeld et al. 2014; McKelvey et al.

2016; Splendiani et al. 2016).

Bartram’s Bass is endemic to the upper Savannah River basin of South Carolina and Georgia. Individuals have been commonly referred to throughout its range as the

Redeye Bass (M. coosae). However, Freeman et al. (2015) identified this species to be more closely related to Shoal Bass, and supported the elevation of Bartram’s Bass to species status. Bartram’s Bass range extends from below the fall line of the mainstem

Savannah River. It has been introduced in the Saluda River of the Santee drainage

(Bettinger 2015). Bartram’s Bass face a multitude of threats including land-use practices, competition, and hybridization with invasive congeners, including Smallmouth Bass (M. dolomieu) and Alabama Bass (M. henshalli) (Oswald et al. 2015; Bangs et al. 2017).

28 Alabama Bass was introduced into the Savannah River basin in the 1980s by anglers to create a sport fishery for the species (Oswald 2007). Prior to the introduction of Alabama

Bass, Bartram’s Bass were found throughout reservoirs of the upper Savannah River, demonstrating the ability to tolerate reservoir habitats. Since their introduction, Alabama

Bass have become widespread in the upper Savannah River basin, and are now colonizing the tributaries (Oswald et al. 2015). Bartram’s Bass and Alabama Bass hybrids have been found in the tributaries; however, it is unknown to what extent hybridization is occurring. The goal of this study was to identify the distribution of Alabama Bass,

Bartram’s Bass, and their hybrids, in the upper Savannah River basin. We quantified effects of landscape-scale variables on the distribution of each species to aid in protecting and enhancing habitat for Bartram’s Bass.

Methods

Study Area

The Savannah River basin spans 27,394 km2, encompassing 15,076 km2 in eastern

Georgia, 11,865 km2 in western South Carolina, and 453 km2 in southwestern North

Carolina (DHEC 2017). There are four large impoundments in the upper Savannah River basin: lakes Jocassee, Keowee, Hartwell, and Russell, as well as smaller reservoirs that impound tributaries upstream of these lakes: lakes Burton, Rabun, Tugaloo, Yonah,

Secession and Stevens Creeks. Land use in the upper Savannah River basin consists of

29 (Omernik 1987) above the fall line. The Piedmont is heavily impacted by development and urbanization, while the Blue Ridge uplands that make up the most upstream reaches of the Savannah River are heavily forested (DHEC 2017). The inner and outer Piedmont ecoregions comprise most of the upper Savannah River watershed (Omernik 1987).

Below the fall line, the Savannah flows southeast along the border of Georgia and South

Carolina before meeting the Atlantic Ocean, encompassing both the Southeastern Plains and Southern Coastal Plain regions (Omernik 1987).

We sampled 160 sites on tributaries to the upper Savannah River to quantify the factors affecting distribution of Bartram’s Bass (Figure 1). Sites were selected to represent a range of stream size and gradient, elevation, watershed- and riparian-scale land use, and distance from impoundments, given access constraints. We collected bass on 300-m reaches using multiple sampling methods over two field seasons (March-

November, 2017 and 2018). Upon arrival at a site, we first sampled by hook-and-line for approximately one hour, as angling is an effective sampling technique for black basses

(Mycko et al. 2018). We then sampled the same reach using both single and double- backpack electrofishing depending on the size of the stream. Fin tissue was collected and preserved for genetic analysis on all captured individuals.

Figure 1. Map of the upper Savannah River and fish collection sites. Land use is categorized in five categories: water, urban, forested, agriculture, and shrub/barren. Management units as defined in Oswald et al. (2015) are outlined in black.

Analysis

Tissue samples of collected individuals were processed at the Hollings Marine

Laboratory in the Population Genetics Laboratory of the South Carolina Department of

Natural Resources (SCDNR). Markers for genetic analyses were adapted based on genetic analyses presented by Bangs et al. (2017). Individuals were classified as one of four pure species (Bartram’s Bass, Largemouth Bass, Smallmouth Bass, Alabama Bass), or as hybrid (crosses between pure species).

31 We gathered data from the National Hydrologic Database Plus Version 2 (NHD) and associated segment-scale attributes to compile predictor variables for a species distribution model for Bartram’s Bass. Land use was reclassified from the National Land

Cover Database (NLCD) 2011 into five categories: water, urban, forested, agriculture, and shrub/barren (Figure 1). Percentages of land use types at the segment scale were calculated by creating a 30-meter buffer around the stream network, and extracting 500- meter stream segments upstream of each site (Frimpong et al. 2005). Watershed-scale percent land cover was obtained through the NHD. We also included geomorphological attributes such as elevation, stream gradient, watershed area, and a binary dummy variable indicating ecoregion (Table 1). To represent distance from sources (i.e., reservoirs) of non-native congeners (e.g., Alabama Bass) as a metric to quantify dispersal potential for these non-native congeners, we calculated distance to nearest downstream impoundment as the fluvial distance from the site to the last riffle upstream of the impoundment, as identified by aerial photographs.

Table 1. List of watershed-scale predictor variables local-scale response variables used in the species distribution mode.

Variable Description Range of values BTB Whether or not Bartram's Bass were 0= No BTB; 1= BTB present at the site Watershed Land Watershed-scale percent land use Water, Urban, Forested, Use classified into 5 categories Agriculture, Shrub/barren Riparian land use Riparian-scale percent land use Water, Urban, Forested, classified into 5 categories Agriculture, Shrub/barren Elevation Elevation of stream segment 190-2,677 feet Stream gradient Stream gradient of stream segment 0.01-63.4 m/km Watershed area Area of watershed that contains a site 1.46-1,757 km2 Ecoregion Binary variable of whether site is in the 0=Blue Ridge; 1=Piedmont Piedmont or Blue Ridge ecoregion Distance to Distance from site to reservoir (last 0.21-154 km reservoir (DR) riffle)

We modeled Bartram’s Bass occurrence as a binary variable by using presence/ absence of pure individuals. We scaled and centered elevation, watershed area, stream gradient, and distance to reservoir variables. We then assessed the data for collinearity based on a threshold of r=0.5. We kept stream gradient, ecoregion, watershed area, distance to reservoir, watershed percent forested, and riparian percent forested in our model as other variables were highly correlated. As elevation was highly correlated with ecoregion, as well as forested, agriculture, and shrub/barren watershed-scale land covers.

All five land cover variables were highly collinear. In our models, we retained only forested land cover from both the watershed and riparian scales, as we considered it to be the most relevant among the different land cover types. We used the lme4 package in R version 3.4.3 (R Development Core Team, 2017) to fit a generalized linear mixed model

33 to quantify effects of variables, and interactions between variables and distance to reservoir. To account for repeated measures (i.e. multiple individuals) within sites, models contained a random intercept of site identity, nested within ecoregion. We tested for spatial autocorrelation of site residuals using the Global Moran’s I spatial autocorrelation function in ArcGIS (ESRI 2011).

To improve interpretation of GLMM interaction terms, we used conditional inference `trees (CITs) to classify sites based on presence or absence of pure Bartram’s

Bass. CITs classify response variables by constructing sequential binary splits (nodes) in a matrix of predictor variables defined by a certain threshold (in this case, the presence or absence of Bartram’s Bass; De’ath & Fabricius, 2000). No post-hoc cross-validation procedures are necessary for CITs (Hothorn et al. 2006), as CITs nodes are based on variable significance tests unlike traditional regression trees. For this analysis, we used the same suite of variables as in the GLMM, only unstandardized. This provides more interpretable thresholds of predictor variables. We fit CITs using the ctree function in the party package and specified that nodes be split based on univariate partitioning with p ≤

0.05. We assessed overall model fit of CITs based on the area under the receiver- operating curve (AUC), and accepted values greater than 0.70 as an adequate model fit.

Results

A total of 787 individuals were collected at 77 sites in 2017 and 2018. Genetic results of a subsample of 241 individuals from 51 sites are included in the current analyses. This subsample was comprised of roughly 5 individuals per site available at the time of genetic analyses. Of these 51 sites, 11 are from the Blue Ridge and 40 from the

34 Piedmont ecoregions. Of those individuals analyzed, 110 samples were pure Bartram’s

Bass, 97 were Largemouth Bass, 33 were hybrids, and 1 was a pure Alabama Bass. We found exclusively pure Bartram’s Bass at only 10 sites, but pure individuals were present at 32 sites, and persisted with congeners at 22 of 51 sites. Hybrids were present at 21 sites, and were rarely found exclusively. Bartram’s Bass were not found at 18 of the 51 sites included in the analyses (Figure 2).

Figure 2. Map of sites in the upper Savannah River basin that are included in the analyses. Sites are color- coded with species present at each site; blue shades represent sites with Bartram’s Bass. “No fish” refers to the lack of black bass.

36 Generalized linear mixed models revealed forested land cover at the watershed scale was the strongest predictor of Bartram’s Bass occurrence. Stream gradient, distance to reservoir, and watershed area did not have significant effects. However, distance to reservoir interacted significantly with stream gradient and watershed-scale forested land cover to influence occurrence of Bartram’s Bass. No interaction was found between distance from reservoir and watershed area, or distance from reservoir and riparian forested land cover (Table 2). Model residuals failed the Moran’s I spatial autocorrelation test (p= 0.2556).

Table 2. Generalized linear mixed effects model results for Bartram’s Bass occurrence in the upper Savannah River.

Parameter Standard Effect estimate Error Z p Distance to reservoir (DR) 0.53 0.51 1.05 0.2930 Forested riparian 0.55 0.39 1.41 0.1589 Forested watershed 1.01 0.45 2.26 0.0236 Stream gradient 0.54 0.48 1.11 0.2660 Watershed area 0.17 0.48 0.35 0.7260 DR : forested riparian -0.15 0.42 -0.37 0.7141 DR : forested watershed -1.42 0.61 -2.31 0.0210 DR : watershed area 0.29 0.42 0.70 0.4857 DR : stream gradient 2.10 0.75 2.81 0.0049

Conditional inference trees helped to inform GLMM results for black bass occurrence at survey sites. The CIT had an AUC value of 0.74, indicating acceptable model fit. As in the GLMM, watershed-scale forested land cover was clearly the most important classifying factor in the CIT (Figure 3); there was the greatest probability of

Bartram’s Bass occurring in sites with watershed-scale forested land cover above 68% with stream gradients less than 8.5, that are greater than 2.5 km from a reservoir.

37 However, distance to reservoir and watershed area contributed to subsequent splits among sites of less than 68% forested watersheds. Sites with less forested cover, and larger watershed areas overall contained higher probability of hybrid presence, however forested cover at the watershed scale contributed to a subsequent split, where sites with less forested cover represented presence of Bartram’s Bass, hybrids, and Largemouth

Bass. Sites with less watershed area and greater distance from reservoirs are more likely to contain no bass, and those closer to reservoirs were more likely to harbor Largemouth

Bass (Figure 3).

Figure 3. Conditional inference tree classifying predictors of Bartram's Bass occurrence. Splits are based on variable-wise univariate significance tests at (alpha)= 0.05. Bar plots represent probability of occurrence of black bass species (“B” = Bartram’s Bass, “H” = Hybrid, “L” = Largemouth Bass, “N” = None). Numbers on the right of histograms represent predicted probability of Bartram’s Bass occurrence.

Discussion

Our findings provide evidence of the widespread nature of introduction and hybridization in the introduced black basses throughout Bartram’s Bass range within the

Savannah River Basin. Hybridization was observed in Twelvemile Creek, Eastatoee

Creek, Little River, Chattooga River, Chauga River, and throughout the Broad River. No pure Bartram’s Bass individuals were collected in the southeastern portion of the upper basin, although Largemouth Bass dominated in this area and were widespread among our

39 sampling sites. Although Bartram’s Bass and Largemouth Bass co-occur at many site, there has not yet been evidence of hybridization between these species. Among hybrids, there was little evidence of hybridization between Bartram’s Bass and Smallmouth Bass, with just two hybrid individuals occurring at one site. This evidences that the two species are capable of hybridizing, however their ranges in the upper Savannah River tributaries prevent hybridization from occurring in many systems. Hybridization between Bartram’s

Bass and Alabama Bass was widespread and frequent. In streams where Bartram’s Bass were present, pure populations were typically observed farther upstream in the system.

Throughout the upper Savannah River basin, it appears there are very different patterns of black bass presence among distinct management units which were outlined in

Oswald et al. (2015). Pure Bartram’s Bass individuals were present in the Tugaloo River,

Seneca River, and Upper Savannah management units, but not in the Middle Savannah.

However, Bartram’s Bass were largely absent from the eastern side of the upper

Savannah River basin. Bartram’s Bass were found throughout the Broad, Little,

Chattooga, and Chauga Rivers. Largemouth Bass dominate the southeastern portion of the upper basin. Some Jocassee and Tugaloo reservoir tributaries show presence of

Bartram’s Bass, despite close proximity to the reservoir.

Reservoirs may be considered a source of nonnative species, as they are hotspots for sport fish introduction (Harbicht et al. 2014). The farther from the reservoir an individual is, the more removed it is from some of the physical and biological impacts of reservoirs, such as habitat simplification, and nonnative species (Falke and Gido 2006).

Distance of native individuals from the reservoirs facilitates the effects of abiotic factors,

40 and allows for interpretation of effects driving dispersal. Our results indicate that pure

Bartram’s Bass are more likely found in areas of greater forested cover with smaller stream gradients that are farther from the reservoirs; Bartram’s Bass were three times more probable at distances greater than 2.5 km from the reservoir even when watershed forested land cover was ideal. Therefore, distribution of Bartram’s Bass mediates the effects of stream gradient and forested cover. Similarly, Harbicht et al. (2014) found that distance to the lake was a strong predictor of admixture between wild and hatchery trout.

Overall, our results indicate that Bartram’s Bass individuals are currently residing in mid- stream locations, as opposed to upstream locations that are too small and possibly too cold and downstream locations harboring nonnatives and increased habitat disturbance.

Many studies have assessed spatial predictors of hybridization between trout species (Hitt et al. 2003; Boyer et al. 2008; Muhlfeld et al 2009; Wagner et al. 2013;

Harbicht et al. 2014; McKelvey et al. 2016; Splendiani et al. 2016; Young et al. 2016).

Studies have found that native fishes are generally more likely to be replaced by nonnatives in areas altered by land use disturbance (Bunn and Arthington 2002;

Largiadèr 2008), where availability and quality of habitats diminishes and subsequently diminishes the native taxa (Muhlfeld et al. 2009). Our results suggest that forest cover at the watershed scale is the only significant factor in predicting the presence of Bartram’s

Bass individuals; however, distance to reservoir interacted significantly with forest cover and stream gradient, suggesting that forest cover and stream gradient are important, but only in the context of distance from the reservoir. Practically, this is because although quality habitats may exist close to reservoirs, it is less likely that Bartram’s Bass

41 individuals will be found in these areas. The evidence that hybrid presence increases with decreasing forested cover at the watershed scale suggests that hybrids tend to do better in areas altered by land use disturbance. Furthermore, forest cover at the riparian scale was not a significant predictor of Bartram’s Bass occurrence, suggesting that individuals are not as impacted by local-scale impacts.

Studies of landscape-level drivers of hybridization have found similar results to ours, in that factors influencing hybridization are often intertwined and complex; for example, McKelvey et al. (2008) found that increased disturbance (road crossings) and increased temperature resulted in increased levels of hybridization. Similarly, Young et al. (2016) found that introgression between trout species was driven by warmer water temperatures, larger-sized streams, and eastern locations. Converse to our findings, land cover at the riparian scale better predicted Shoal Bass presence than at the watershed scale in the Apalachicola-Chattahoochee-Flint (ACF) Basin (Taylor et al. 2017). This is likely due to the fact that Shoal Bass are habitat-specialists who require particular types of stream habitats for different stages of their life history (ie. reproduction: shoal habitats).

Range loss is a common result of hybridization in native black bass populations

(Jackson 2002; Koppelman and Garrett 2002; Littrell et al. 2007; Dakin et al. 2015;

Earley and Sammons 2015; Nagid et al. 2015; Peterson 2015). Bartram’s Bass were found in reservoirs prior to, and after, the introduction of nonnative congeners (Barwick et al. 2006; Oswald 2007; Bangs et al. 2017). However, Bartram’s Bass in two reservoirs of the Savannah River have recently been observed as extirpated, and numbers are in

42 rapid decline in two more (Barwick et al. 2006; Oswald 2007; Oswald et al. 2015; Bangs et al. 2017). There is considerable variation in affinity for lentic habitats among the black basses. In their native range, Redeye Bass inhabit small 3rd or 4th order streams with cooler temperatures, and have been found at gradients of 4-7 m/km in the Coosa drainage

(Kelly et al. 1981; Koppelman and Garrett 2002). Conversely, Alabama Bass inhabit medium- to large-sized rivers and do well in impoundments of the Mobile River basin

(Rider and Maceina 2015), and have maintained healthy populations in impoundments where they are introduced (Pierce and Van Den Avyle 1997; Moyle 2002; Bangs et al.

2017). In the Savannah River, all four species of black bass exhibit some tolerance for lentic systems. Bartram’s Bass have demonstrated the potential to thrive in areas of lower stream gradients when unaltered by nonnative congeners (Leitner et al. 2015). Our results show that Bartram’s Bass populations are now found less in areas closer to reservoirs with lower stream gradients overall regardless of habitat quality, and instead persist farther upstream in tributaries. Because Bartram’s Bass were found in healthy numbers in the reservoirs of the upper Savannah River prior to Alabama bass introduction, there is reason to believe their populations close to the reservoirs would follow a similar trend of decline as Alabama Bass dispersed from reservoirs into low gradient stream habitats.

Trends similar to those of this study have been concluded in other Micropterus species facing similar threats; Shoal Bass in the ACF basin are restricted to relatively small areas of its native range due to the influence of nonnative congeners, land cover, and fragmentation (Taylor et al. 2017). It is speculated that interactions with congeners has caused exclusion of Redeye Bass from reservoirs (Parsons 1954; Barwick and Moore

43 1983; Koppelman and Garrett 2002). Guadalupe Bass have also experienced hybridization with Smallmouth Bass throughout their range and, prior to recent reintroduction efforts, their pure populations were nearly extirpated (Koppelman and

Garrett 2002).

Many tributaries to the Savannah River impoundments contain structures once thought to be potential barriers to upstream fish movement, which may guard the pure populations that occur above barriers; generally, pure individuals of Bartram’s Bass have previously been observed persisting above barrier structures (natural and anthropogenic) in many systems (Coneross Creek, Chauga River, and Stevens Creek), and intermingling with hybrids above barriers in other systems (Twelvemile River and Little River). Our results indicate that there are hybrid individuals found above some barriers (Tallulah

River, Chattooga River, Twelvemile Creek, and Little River). It is likely the hybrid individuals found above barriers is a symptom of anthropogenic introduction above barriers. Management practices best suited for retaining pure pockets of Bartram’s Bass may include keeping a barrier to prevent invasive movement further upstream, and subsequently educating the public about impacts of nonnative species and limiting the translocation of species outside of their native range (Bean et al. 2013).

Estimating abiotic-based predictive distributions aids in our ability to quantify species habitat relationships, range-loss estimation, remnant distributions, and allows for identification of suitable restoration sites if necessary for future management (Guisan and

Thuiller 2005). The purpose of this study was to identify the abiotic factors that contribute to the dispersal of riverine black bass in the Savannah River. Developing

44 conservation strategies for species is particularly difficult without information specific to populations, therefore evaluating factors affecting individuals is important to the conservation of species (Rabeni and Sowa 1996). Understanding how abiotic factors influence fishes is an established concept (Wiens 2002; Gozlan et al. 2010), and is necessary for effective management of rare endemic species. Future research on rare black bass populations should implement landscape-level analyses, like those presented here, to further understand drivers of distribution within native ranges.

There are a variety of management measures that could be taken to conserve pure pockets of Bartram’s Bass. Management should seek to restore habitat at the watershed scale for hybrid-influenced areas, and focus on maintaining habitat for pure individuals.

Riparian-scale forested cover had little effect on Bartram’s Bass distribution, therefore restoration at the local riparian scale would not likely have much of an impact on the population. Conservation stocking may be an option for this species to reverse genetic effects of introgression in some stream segments. Such stocking has been implemented successfully in pockets of Guadalupe Bass in the South Llano River of Texas (Bean et al.

2013) and in pockets of Shoal Bass in the Chattahoochee River, below the Morgan Falls

Dam of Georgia (Taylor et al. 2018). Although stocking would not ensure conservation of a pure population, stocking has the potential to overwhelm the gene pool with native alleles. For this method to be successful for Bartram’s Bass, stocking efforts would have to focus on areas of suitable habitat, and/or in locations where hybrids have not already dominated. Suitable sites may include those in watersheds of greater than 75% forested cover, at least 2.5 km from a reservoir, with stream gradient under 8.5; suitable habitat

45 should also consider areas for reproduction consisting of slow water velocity (<0.1 m/s) pockets along stream banks. Stocked individuals would need to be reared from brood- stock that has been screened against nonnative alleles to ensure pure genetics are being contributed to the natural population, and should consider management units based on genetic provinces identified by Oswald et al. (2015). Restoration stocking efforts have been successful for the Guadalupe Bass, reducing hybridization rates with smallmouth bass by up to 9% per year (Fleming et al. 2015). However, this method is costly, and would require heavy public involvement to be successful. Another option would be the removal of nonnative individuals where they occur, however this method requires a tactical approach to avoid missing hybrids and nonnative species in systems where they could continue to spread. This approach may be insufficient on its own, as it is unlikely managers would be able to remove enough individuals to prevent future reproduction; furthermore, field identification of hybrid individuals can be difficult. Possibly a combination of methods may be best for prolonging pure populations of Bartram’s Bass.

Furthermore, due to the relative lack of public knowledge surrounding this species within its native range, management actions should seek to educate and advocate for Bartram’s

Bass whenever possible. Future directions should seek to find proper and realistic management solutions for this species.

46 GENERAL CONCLUSION

Bartram’s Bass is an endemic black bass found only in the Savannah River basin of South Carolina and Georgia. This research was initiated after previous South Carolina

Department of Natural Resources (SCDNR) sampling of tributaries revealed that

Bartram’s Bass and their hybrids with nonnative congeners, primarily Alabama bass, were co-distributed in some tributaries. Thus, we set out to define the nesting preferences of Bartram’s Bass, and to determine the distribution of current pure Bartram’s Bass individuals and the factors driving them.

Results of this study shed light on how we may better manage pure populations moving forward. Over the two spawning seasons, we detected 75 nests, of which 39 were genetically identified as pure Bartram’s Bass. We found that water velocity was the most important factor for nesting Bartram’s Bass. Specifically, we observed that individuals select slow-moving pockets near shore for nesting, and particularly for refuge during years of increased flow. We conclude that depth did not play a role in nest selection, as nesting individuals selected for a variety of depths. Bartram’s Bass used a variety of substrates for nesting, largely dependent upon those available in the slow velocity pockets they select for. The preferred substrate used in nests in both breeding years combined was primarily silt (36%), cobble (31%), and gravel (21%), whereas the most available substrate observed in transects was bedrock (23%) and cobble (23%). On average, nests were 1.84 ± 0.25 m from the nearest bank, and 4.67 ± 0.56 m from the nearest upstream flow influence. Our results provide knowledge of quality nesting

47 habitats for endemic Bartram’s Bass, which will be critical for future management of this species and our understanding of hybridization with nonnative congeners.

This study documents where different black bass species are found in the tributary systems, and the factors that have a role in their distributions. Pure Bartram’s Bass were observed in the Broad, Little, Chattooga, and Chauga Rivers, as well as sites in close proximity to Lake Jocassee. Hybrids were mainly observed in tributaries of the northeastern portion of the upper Savannah River basin, but also co-occurred with pure

Bartram’s Bass individuals. There was a lack of Bartram’s Bass individuals in the southeastern portion of the upper basin. Largemouth Bass were also widespread among our sampling sites. Among hybrids, there was little evidence of hybridization between

Bartram’s Bass and Smallmouth Bass, and high evidence of Bartram’s Bass and Alabama

Bass hybridization. No hybrids were identified as Bartram’s Bass and Largemouth Bass, similar to results of previous SCDNR sampling. In streams where Bartram’s Bass were present, pure individuals were typically observed farther upstream in the system.

Results of this study suggest abiotic factors play a role in determining occurrence of pure Bartram’s Bass, and that future land management activities could have an impact on this species. Our results indicated that forested land cover at the watershed scale was the only significant predictor of Bartram’s Bass occurrence. Stream gradient, watershed area, and distance to reservoir were also found as key mechanisms in determining

Bartram’s Bass presence. As such, fewer Bartram’s Bass individuals were found closer to reservoirs even when forested cover and stream gradient was at ideal levels. This

48 suggests that stream gradient and forested cover are important, however only in the context of distribution from reservoirs.

Based on the results of this study, management of Bartram’s Bass should focus on areas of the basin that still harbor pure individuals, and those that have the potential to host successful pure populations. Land management of the northwestern region is dominated by federal and state managed lands that are mostly protected from future development and pollutants; these areas may therefore be the most promising when considering future management. The Broad River also harbors many sites with pure individuals, as well as sites where hybrids and pure coexist; this may be a system to consider for future management. Efforts to combat the spread of hybridization have been successful in other systems when stocking of the native species, and eradication of nonnative and hybrid individuals are implemented together (Bean et al. 2013; Fleming et al. 2015). It would be wise to select locations for this type of management that incorporate appropriate habitats for Bartram’s Bass, as defined in this study; suitable sites may include those in watersheds of greater than 75% forested cover, at least 2.5 km from a reservoir, with smaller stream gradients; suitable habitat should also consider areas for reproduction consisting of slow water velocity (<0.1 m/s) pockets along stream banks.

Managing for pure Bartram’s Bass should be of utmost importance moving forward, as we have observed a lack of Bartram’s Bass individuals in areas that they were previously found, specifically in the eastern portion of the upper basin. Trends of hybridization in other endemic populations of black bass have provided cause to act quickly to prevent further spread of nonnative species in this basin. It is important to consider how various

49 management actions have fared in other populations of rare black basses experiencing similar threats in their respective ranges. Next steps for management of Bartram’s Bass should implement the results of this study in decision-making.

Hybridization is a mechanism that acts quickly on native populations (Huxel

1999). Since their introduction into the Savannah River Basin, Alabama Bass have dominated the reservoir systems, and spread into tributaries. We found that hybrids of these nonnative species and Bartram’s Bass occur in mid-upstream locations, with the exception of few pure populations protected by barriers. Although hybridization between

Bartram’s Bass and Smallmouth Bass was documented at a small amount, it should be monitored and taken into consideration for future management. Future studies and management should investigate the reality and implications of implementing eradication for nonnative species and/or stocking efforts for Bartram’s Bass throughout their range in the upper Savannah River basin.

50 Appendix A

Supplemental Tables

Table A.1. Sites included in chapter one analyses. Table include site identities, coordinates, and number of nests found at each site as well as the number of pure Bartram's Bass nests found at each site.

Site Latitude Longitude Nests Pure SC01 34.9719 -83.1147 0 0 SC02 34.9193 -83.1686 31 12 SC03 34.8155 -83.3065 14 10 SC04 34.7547 -83.3267 4 2 SC05 34.8327 -83.1748 0 0 SC06 34.7873 -83.2104 7 4 SC07 34.7179 -83.1772 0 0 SC08 34.6856 -83.1514 0 0 SC09 34.6636 -83.1603 0 0 SC11 34.6675 -83.0283 0 0 SC12 34.6497 -82.9916 0 0 SC13 34.7690 -83.0114 1 1 SC14 34.8717 -83.0376 0 0 SC15 34.8724 -83.0239 0 0 SC16 34.8741 -83.0203 0 0 SC17 34.8621 -82.9928 2 0 SC18 34.8405 -82.9893 0 0 SC19 34.8367 -82.9799 3 0 SC20 34.9867 -82.8458 7 5 SC21 34.9585 -82.8526 1 1 SC22 34.9464 -82.8555 0 0 SC36 34.6823 -83.1451 1 1 SC37 34.6819 -83.1468 3 3 SC38 34.8713 -83.0088 0 0 SC39 34.8442 -83.0170 0 0 GA06 34.7573 -83.3966 0 0 GA08 34.6676 -83.3649 1 0 Total 75 39

51 Table A.2. Sites of fish collection for Chapter 2. Included are site identifiers and coordinates.

Site Latitude Longitude Site Latitude Longitude DNR 000 34.3337 -82.6480 DNR31 34.3834 -82.5772 DNR 04 34.2956 -82.6192 DNR64 34.3534 -82.7861 DNR 109 34.2742 -82.7322 DNR66 34.2401 -82.3018 DNR 111 34.3098 -82.4370 GA01 34.9019 -83.2538 DNR 1111 34.3102 -82.6186 GA02 34.8394 -83.3370 DNR 1112 33.5147 -81.9935 GA03 34.8382 -83.3598 DNR 1113 34.2306 -82.4678 GA04 34.7789 -83.4154 DNR 1114 33.9529 -81.9681 GA05/06 34.7770 -83.3985 DNR 1115 33.9241 -81.9387 GA07 34.6788 -83.3441 DNR 117 33.6314 -82.0614 GA08 34.6676 -83.3649 DNR 145 34.0133 -82.4682 GA09 34.6193 -83.2977 DNR 157 33.9277 -82.0248 GA10 34.5262 -83.1854 DNR 168 34.3050 -82.4391 GA11 34.4821 -83.1223 DNR 2 34.1132 -82.4776 GA12 34.4512 -83.0423 DNR 222 34.3086 -82.7373 GA13 34.5136 -83.3221 DNR 23 33.7947 -82.1462 GA14 34.4020 -83.1870 DNR 333 34.3555 -82.7517 GA15 34.3231 -83.1864 DNR 444 34.4197 -82.7724 GA16 34.2790 -83.1776 DNR 50 34.3894 -82.5472 GA17 34.2399 -83.1790 DNR 55 34.5471 -82.5404 GA18 34.3972 -83.3186 DNR 555 33.7067 -82.1475 GA19 34.3424 -83.2541 DNR 59 34.5193 -82.6082 GA20 34.3197 -83.2130 DNR 7 34.0246 -82.2114 GA21 34.1820 -83.1470 DNR 70 34.0043 -82.0932 GA22 34.1564 -83.1004 DNR 77 33.8893 -82.0020 GA23 34.1572 -83.0832 DNR 777 33.9860 -82.3772 GA24 34.0319 -83.0093 DNR 78 34.4532 -82.7314 GA25 34.0003 -82.8857 DNR 8 33.9433 -82.2210 GA26 33.9416 -82.8252 DNR 84 33.9253 -82.1751 GA27 33.9841 -82.8012 DNR 888 34.1561 -82.5171 GA28 34.0115 -82.6325 DNR 97 33.7995 -82.1236 GA29 34.1420 -82.8394 DNR 999 34.1056 -82.5309 GA30 34.2252 -82.8284 DNR03 34.0431 -82.0613 GA31 34.9351 -83.5480 DNR100 34.1123 -82.3066 GA32 34.7936 -83.4269 DNR103 34.1352 -82.3256 GA33 34.5554 -83.2877 DNR26 34.0005 -82.3520 GA34 34.2756 -83.2670

52 Site Latitude Longitude Site Latitude Longitude GA35 34.2774 -83.3727 GA73 34.3983 -83.5790 GA36 34.3075 -83.5433 GA74 34.2630 -83.4467 GA37 34.8582 -83.5847 GA75 34.3098 -83.4650 GA38 34.9193 -83.5649 GA76 34.8302 -83.3427 GA39 34.2476 -83.4038 GA77 34.8581 -83.5124 GA40 34.8480 -83.5961 GA78 34.8940 -83.5131 GA41 34.5517 -83.3628 GA79 34.1442 -83.0073 GA42 34.1322 -83.2684 SC01 34.9719 -83.1147 GA43 34.1318 -83.2486 SC02 34.9193 -83.1686 GA44 34.0655 -83.1919 SC03 34.8155 -83.3065 GA45 34.0125 -83.1915 SC04 34.7590 -83.3201 GA46 34.0533 -83.0369 SC05 34.8327 -83.1748 GA47 34.4081 -83.3017 SC06 34.7873 -83.2104 GA48 34.4692 -83.4917 SC07 34.7179 -83.1772 GA49 34.8331 -83.6067 SC08 34.6856 -83.1514 GA50 34.8027 -83.4285 SC09 34.6636 -83.1603 GA51 34.4128 -83.5186 SC10 34.6316 -83.1747 GA52 34.4041 -83.5888 SC11 34.6675 -83.0283 GA53 34.4386 -83.5243 SC12 34.6497 -82.9916 GA54 34.4703 -83.4843 SC13 34.7690 -83.0114 GA55 34.3456 -83.4730 SC14 34.8717 -83.0376 GA56 34.4391 -83.4270 SC15 34.8724 -83.0239 GA57 34.4269 -83.3690 SC16 34.8741 -83.0203 GA58 34.3728 -83.3782 SC17 34.8621 -82.9928 GA59 34.2917 -83.4088 SC18 34.8405 -82.9893 GA60 34.2491 -83.2709 SC19 34.8367 -82.9799 GA61 34.0461 -83.1273 SC20 34.9867 -82.8458 GA62 33.9852 -83.1343 SC21 34.9585 -82.8526 GA63 34.3971 -83.6191 SC22 34.9464 -82.8555 GA64 34.1682 -83.3081 SC23 34.8125 -82.7468 GA65 34.6380 -83.4257 SC24 34.8027 -82.7495 GA66 34.9826 -83.1913 SC25 34.8590 -82.7450 GA67 34.6017 -83.3727 SC26 34.7625 -82.7920 GA68 34.4482 -83.2278 SC27 34.7190 -82.7358 GA69 34.3080 -83.3382 SC28 34.7048 -82.7568 GA70 34.4519 -83.3599 SC29 34.6753 -82.7845 GA71 34.3382 -83.4877 SC30 34.6643 -82.7961 GA72 34.2801 -83.5381 SC31 34.6364 -82.8043

53 Site Latitude Longitude SC32 34.6796 -82.6506 SC33 34.6499 -82.7031 SC34 34.6277 -82.7469 SC35 34.6095 -82.7628 SC36 34.6823 -83.1451 SC37 34.6819 -83.1468 SC38 34.7691 -83.1158 SC39 34.9671 -82.9020 SC40 35.0041 -83.0545 SC41 35.0509 -82.8129 SC42 34.9357 -83.0018 SC43 35.0027 -83.0249

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